Fragmenting machines or waste recycling machines are designed to splinter and fragment wastes under tremendous impacting forces. Operationally, waste materials are fed to a fragmenting zone or grinding chamber by power feeding means. Once the waste materials are within the fragmenting zone or grinding chamber, a powered fragmenting rotor that is rotating at high speed and comprising impacting and shearing teeth is encountered. The resulting impact results in the fragmentation and/or comminution of the waste materials to a desired particle size. Generally, the rotor rotates at about 1800-2500 r.p.m. Thus, a tremendous force is generated at the point of impact between the waste material and the impacting rotor teeth. Certain material having unacceptably high density, e.g., heavy pieces of steel, are ungrindable and may cause significant damage to the fragmenting machine, resulting in expense and machine downtime. Thus, a need exists for detecting the potentially damaging material and for preventing or minimizing such damage upon detection.
A wide range of methods and associated devices are currently used for monitoring performance characteristics of industrial equipment. Generally, the monitoring devices generally are placed on, or near, the equipment or points of interest thereof. Once positioned, the devices monitor certain signals generated by the equipment and the performance of the equipment is then evaluated by, inter alia, analyzing the signal data. These signals are utilized to monitor the performance of the equipment over its operating life. For example, vibration monitoring may be used to monitor the frictional energy created by the equipment's moving parts, e.g., bearings, couplings, gear mesh and the like. Low frequency vibration measurements may indicate a bearing in an advanced state of wear and potentially provide information about the root cause of the failure such as misalignment, imbalance, etc. High frequency vibration monitoring may detect such wear at an earlier stage, triggering alarms before the bearing enters a failure state due to wear and tear. High frequency vibration monitoring may also allow for maximization of preventive maintenance programs by indicating when, for example, it is necessary or desirable to grease or otherwise lubricate the subject machine components.
However, none of the currently described methods allow for detection of potentially ungrindable material within the grinding or fragmenting chamber of a waste fragmenting machine. Nor does any currently known waste fragmenting machine combine detection of potentially ungrindable material with additional steps to minimize any damage resulting from the impact of the rotor teeth on the potentially ungrindable material.
Accordingly, there remains a need for a method that limits or prevents damage to a fragmenting machine by detecting unacceptably dense material within the grinding chamber or fragmenting zone and then initiating steps to minimize any damage. The present invention addresses this need.